Calculate a monthly loan payment from a fixed term or calculate payoff time from a fixed monthly payment, with total interest and a full amortization schedule.
Calculator
Payment Results
Review the payment, payoff time, borrowing cost, and month-by-month balance.
Principal and Interest
Calculation Details
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Monthly Amortization Schedule
| Month | Payment | Principal | Interest | Ending balance |
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Monthly payment or payoff term
This payment calculator answers either side of a common fixed-rate loan decision. Fixed Term calculates the monthly payment needed to repay a balance within a chosen number of years and months. Fixed Payments calculates how long repayment takes when the monthly amount is already known.
Fixed-term payment formula
For a fully amortizing loan, each payment covers that month's interest and reduces principal. P is the starting principal, r is the monthly interest rate, and n is the number of monthly payments.
monthly payment = P x r x (1 + r)^n / ((1 + r)^n - 1)
At a zero interest rate, the payment is simply principal divided by the number of months. A $200,000 loan at 6% for 15 years produces a monthly payment of about $1,687.71 before fees, taxes, or insurance.
Fixed monthly payment formula
When payment is known, the calculator rearranges the amortization equation to solve for the number of months. The monthly payment must be greater than the first month's interest. Otherwise the balance cannot decline under the entered assumptions.
months = -ln(1 - principal x monthly rate / payment) / ln(1 + monthly rate)
How the amortization schedule works
Interest is calculated from the balance at the beginning of each month. The rest of the payment reduces principal. Because the balance generally falls over time, the interest portion declines while the principal portion rises. The final payment can be smaller than the regular payment so the schedule does not overpay the balance.
Interest rate versus APR
This calculator applies the entered percentage as a fixed nominal annual rate divided by 12. It does not independently add origination fees, points, closing costs, insurance, or other charges. The Consumer Financial Protection Bureau explains that APR is a broader borrowing-cost measure that can include the interest rate and certain fees. Use the disclosed APR when comparing offers if you want those eligible costs reflected in the rate.
Choosing a term or payment
A longer term usually lowers the required monthly payment but raises total interest. A larger fixed payment shortens the payoff period and normally lowers interest. Compare both modes using the same principal and rate. For mortgages with taxes and insurance, use the mortgage calculator; for multiple compounding and payment frequencies, use the loan calculator.
Important assumptions
The calculation assumes a fixed rate, one payment each month, no missed or late payments, and no fees or prepayment penalties. Actual lenders can use daily interest, different rounding, payment dates, variable rates, or other contractual rules. Review the promissory note and lender disclosures before making a borrowing decision.
Frequently asked questions
Why is my fixed payment too low?
If the payment does not exceed monthly interest, it cannot reduce principal. Increase the payment, lower the balance, or use a lower rate.
Does an extra monthly payment reduce interest?
Usually yes. In Fixed Payments mode, enter the total amount you plan to pay each month; the schedule shows the shorter estimated term and reduced interest.
Does this calculate a payoff date?
It calculates the number of monthly payments and expresses that duration in years and months. It does not account for a lender's exact billing date or daily-interest convention.